Pressure washer capacitor replacement
in [Repair]
|
Prev: Repaired - MAG LCD TV Dead - Model 3200 MA-32EF1AC Options
Next: Philips CD-670 (CDM2/10 transport) sometime fails the startup sequence, ...sometime not.
From: Foo on 28 Sep 2009 11:06 A few years ago, the motor capacitor from my pressure washer exploded, it was a large 50uF non-polarized, plastic-cased run capacitor for a 230V, 2750W motor. Interestingly, it didn't stop the motor right away but it couldn't restart when shut down. Its case read ILCEA K 45 5000 50uF +/- 5%b 450V HPFPU. Because the device was over ten years old, I didn't bother to repair it but kept it anyway, until a few months ago when someone gave me four large alumin(i)um-cased caps: 13uF 13uF 14uF and 10uF (non polarized, 450V max or so, all from Bosch). So I decided to wire them in parallel in place of the old one, and it worked as before even under maximum load. After 10 minutes of use, I stopped the motor to make sure the capacitors were not overheating and found that the two 13uF caps were hotter than the others (still able to touch them with my bare hand, but the two others were still at room temperature). Does it mean that only those two actually work, do you think it's safe to continue operating the device, or will they keep heating up until they meet their fate too? Thanks. -- Foo
From: PlainBill47 on 28 Sep 2009 12:20 On Mon, 28 Sep 2009 15:06:53 +0000 (UTC), Foo <moo(a)not.here> wrote: >A few years ago, the motor capacitor from my pressure washer exploded, >it was a large 50uF non-polarized, plastic-cased run capacitor for >a 230V, 2750W motor. Interestingly, it didn't stop the motor right away >but it couldn't restart when shut down. > >Its case read ILCEA K 45 5000 50uF +/- 5%b 450V HPFPU. > >Because the device was over ten years old, I didn't bother to repair >it but kept it anyway, until a few months ago when someone gave me four >large alumin(i)um-cased caps: 13uF 13uF 14uF and 10uF (non polarized, >450V max or so, all from Bosch). > >So I decided to wire them in parallel in place of the old one, and it >worked as before even under maximum load. > >After 10 minutes of use, I stopped the motor to make sure the capacitors >were not overheating and found that the two 13uF caps were hotter than >the others (still able to touch them with my bare hand, but the two others >were still at room temperature). > >Does it mean that only those two actually work, do you think it's safe >to continue operating the device, or will they keep heating up until they >meet their fate too? > >Thanks. It is likely that only the two that are heating up actually work. If you wish to use the pressure washer I would suggest buying the correct part. Cobbling together several capacitors for a piece of equipment that is handling water at high pressure doesn't seem safe. PlainBill
From: Foo on 28 Sep 2009 18:29 On 2009-09-28, PlainBill47(a)yahoo.com <PlainBill47(a)yahoo.com> wrote: > On Mon, 28 Sep 2009 15:06:53 +0000 (UTC), Foo <moo(a)not.here> wrote: > >>A few years ago, the motor capacitor from my pressure washer exploded, >>it was a large 50uF non-polarized, plastic-cased run capacitor for >>a 230V, 2750W motor. Interestingly, it didn't stop the motor right away >>but it couldn't restart when shut down. >> >>Its case read ILCEA K 45 5000 50uF +/- 5%b 450V HPFPU. >> >>Because the device was over ten years old, I didn't bother to repair >>it but kept it anyway, until a few months ago when someone gave me four >>large alumin(i)um-cased caps: 13uF 13uF 14uF and 10uF (non polarized, >>450V max or so, all from Bosch). >> >>So I decided to wire them in parallel in place of the old one, and it >>worked as before even under maximum load. >> >>After 10 minutes of use, I stopped the motor to make sure the capacitors >>were not overheating and found that the two 13uF caps were hotter than >>the others (still able to touch them with my bare hand, but the two others >>were still at room temperature). >> >>Does it mean that only those two actually work, do you think it's safe >>to continue operating the device, or will they keep heating up until they >>meet their fate too? >> >>Thanks. > It is likely that only the two that are heating up actually work. If > you wish to use the pressure washer I would suggest buying the correct > part. Cobbling together several capacitors for a piece of equipment > that is handling water at high pressure doesn't seem safe. I agree that it would be the best solution, and as Meat Plow suggested above, using capacitors of different values in parallel cannot be good. However, finding a good replacement part won't be easy (I will have to go out or something equally complicated) and probably a bit expensive. In the meantime, I was thinking about an alternate solution to avoid damaging my capacitors: since the motor seems able to run without them, what if I disconnect them after it's started? Alternatively, I'd like to know what would happen if I use less capacitance, using 2x13uF or 14uF only. Will it be a power/performance problem or will something get damaged? -- Foo
From: webpa on 28 Sep 2009 18:35 On Sep 28, 5:29 pm, Foo <m...(a)not.here> wrote: > On 2009-09-28, PlainBil...(a)yahoo.com <PlainBil...(a)yahoo.com> wrote: > > > > > On Mon, 28 Sep 2009 15:06:53 +0000 (UTC), Foo <m...(a)not.here> wrote: > > >>A few years ago, the motor capacitor from my pressure washer exploded, > >>it was a large 50uF non-polarized, plastic-cased run capacitor for > >>a 230V, 2750W motor. Interestingly, it didn't stop the motor right away > >>but it couldn't restart when shut down. > > >>Its case read ILCEA K 45 5000 50uF +/- 5%b 450V HPFPU. > > >>Because the device was over ten years old, I didn't bother to repair > >>it but kept it anyway, until a few months ago when someone gave me four > >>large alumin(i)um-cased caps: 13uF 13uF 14uF and 10uF (non polarized, > >>450V max or so, all from Bosch). > > >>So I decided to wire them in parallel in place of the old one, and it > >>worked as before even under maximum load. > > >>After 10 minutes of use, I stopped the motor to make sure the capacitors > >>were not overheating and found that the two 13uF caps were hotter than > >>the others (still able to touch them with my bare hand, but the two others > >>were still at room temperature). > > >>Does it mean that only those two actually work, do you think it's safe > >>to continue operating the device, or will they keep heating up until they > >>meet their fate too? > > >>Thanks. > > It is likely that only the two that are heating up actually work. If > > you wish to use the pressure washer I would suggest buying the correct > > part. Cobbling together several capacitors for a piece of equipment > > that is handling water at high pressure doesn't seem safe. > > I agree that it would be the best solution, and as Meat Plow suggested > above, using capacitors of different values in parallel cannot be good. > > However, finding a good replacement part won't be easy (I will have to go > out or something equally complicated) and probably a bit expensive. > > In the meantime, I was thinking about an alternate solution to avoid > damaging my capacitors: since the motor seems able to run without them, > what if I disconnect them after it's started? > > Alternatively, I'd like to know what would happen if I use less capacitance, > using 2x13uF or 14uF only. Will it be a power/performance problem or will > something get damaged? > > -- > Foo It is likely the capacitor does nothing except participate in generating a pseudo-rotating stator field during starting. Once the motor is running, it does nothing at all.
From: Sjouke Burry on 28 Sep 2009 18:54
webpa(a)aol.com wrote: > On Sep 28, 5:29 pm, Foo <m...(a)not.here> wrote: >> On 2009-09-28, PlainBil...(a)yahoo.com <PlainBil...(a)yahoo.com> wrote: >> >> >> >>> On Mon, 28 Sep 2009 15:06:53 +0000 (UTC), Foo <m...(a)not.here> wrote: >>>> A few years ago, the motor capacitor from my pressure washer exploded, >>>> it was a large 50uF non-polarized, plastic-cased run capacitor for >>>> a 230V, 2750W motor. Interestingly, it didn't stop the motor right away >>>> but it couldn't restart when shut down. >>>> Its case read ILCEA K 45 5000 50uF +/- 5%b 450V HPFPU. >>>> Because the device was over ten years old, I didn't bother to repair >>>> it but kept it anyway, until a few months ago when someone gave me four >>>> large alumin(i)um-cased caps: 13uF 13uF 14uF and 10uF (non polarized, >>>> 450V max or so, all from Bosch). >>>> So I decided to wire them in parallel in place of the old one, and it >>>> worked as before even under maximum load. >>>> After 10 minutes of use, I stopped the motor to make sure the capacitors >>>> were not overheating and found that the two 13uF caps were hotter than >>>> the others (still able to touch them with my bare hand, but the two others >>>> were still at room temperature). >>>> Does it mean that only those two actually work, do you think it's safe >>>> to continue operating the device, or will they keep heating up until they >>>> meet their fate too? >>>> Thanks. >>> It is likely that only the two that are heating up actually work. If >>> you wish to use the pressure washer I would suggest buying the correct >>> part. Cobbling together several capacitors for a piece of equipment >>> that is handling water at high pressure doesn't seem safe. >> I agree that it would be the best solution, and as Meat Plow suggested >> above, using capacitors of different values in parallel cannot be good. >> >> However, finding a good replacement part won't be easy (I will have to go >> out or something equally complicated) and probably a bit expensive. >> >> In the meantime, I was thinking about an alternate solution to avoid >> damaging my capacitors: since the motor seems able to run without them, >> what if I disconnect them after it's started? >> >> Alternatively, I'd like to know what would happen if I use less capacitance, >> using 2x13uF or 14uF only. Will it be a power/performance problem or will >> something get damaged? >> >> -- >> Foo > > It is likely the capacitor does nothing except participate in > generating a pseudo-rotating stator field during starting. Once the > motor is running, it does nothing at all. The cap produces a pseudo-rotating stator field, and is dragging the rotor around, even after startup. If you leave the cap out after starting, the bulk of the torque is lost. That is,for the motors designed with a permanent cap. |